National Caries Program is committed to identifying, testing and promoting the use of safe and effective noncariogenic alternatives to sucrose. Xylitol has been shown to be noncariogenic in humans and animals. Claims have also been made that it is also cariostatic. The purpose of the present investigation was to determine the effect of administering xylitol either in food and drinking water or by gastric intubation or lactoperexidase activity in parotid and submandibular saliva in primates. Lactoperoxidase is an antimicrobial enzyme found in many mammalian secretions. It was found that the ingestion of xylitol was associated with a significant increase in the activity of salivary lactoperoxidase. The concentration of protein was also increased. Higher lactoperoxidase activity was found in parotid more than in submandibular saliva. Administration by means of gastric intubation of 2-4 g of xylitol or sorbitol per day to monkeys resulted in almost similar increases of salivary lactoperoxidase activity. These results show that specific sugar alcohols have a selective effect on the biochemical properties of saliva.